# -*- coding: utf-8 -*-

import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
	"""docstring for Bullet"""
	def __init__(self, ai_settings,screen,ship):
		super(Bullet, self).__init__()
		self.screen = screen
		
		#在(0,0)处创建一个表示子弹的矩形,再设置正确的位置
		self.rect = pygame.Rect(0,0,ai_settings.bullet_width,ai_settings.bullet_height)		
		self.rect.centerx = ship.rect.centerx
		self.rect.top = ship.rect.top

		self.y = float(self.rect.y)

		self.color = ai_settings.bullet_color
		self.speed_factor = ai_settings.bullet_speed_factor

	def update(self):
		self.y -= self.speed_factor
		self.rect.y = self.y

	def draw_bullet(self):
		pygame.draw.rect(self.screen,self.color,self.rect)
